how much zucchini? could you give me cups of grated zucchini?

Zucchini has a lot of water so prepare yourself to have more on hand than you think you will need.

The recipe seems forgiving enough that you don't need to be extremely precise with the amount of grated zucchini. I would expect to get somewhere between 2/3 - 1 cup of grated zucchini from a medium-sized specimen.